package com.hmdp.service.impl;

import ch.qos.logback.core.util.TimeUtil;
import cn.hutool.core.bean.BeanUtil;
import cn.hutool.core.bean.copier.CopyOptions;
import cn.hutool.core.util.BooleanUtil;
import cn.hutool.core.util.StrUtil;
import cn.hutool.json.JSONObject;
import cn.hutool.json.JSONUtil;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.hmdp.dto.Result;
import com.hmdp.entity.Shop;
import com.hmdp.mapper.ShopMapper;
import com.hmdp.service.IFollowService;
import com.hmdp.service.IShopService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.CacheClient;
import com.hmdp.utils.RedisData;
import com.hmdp.utils.SystemConstants;
import jodd.util.StringUtil;
import org.springframework.data.geo.Distance;
import org.springframework.data.geo.GeoResult;
import org.springframework.data.geo.GeoResults;
import org.springframework.data.redis.connection.RedisGeoCommands;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.domain.geo.GeoReference;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;
import sun.util.resources.LocaleData;

import javax.annotation.Resource;

import java.time.LocalDateTime;
import java.util.*;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;
import java.util.concurrent.TimeUnit;

import static com.hmdp.utils.RedisConstants.*;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
public class ShopServiceImpl extends ServiceImpl<ShopMapper, Shop> implements IShopService {
    @Resource
    private StringRedisTemplate stringRedisTemplate;

    @Resource
    private CacheClient cacheClient;

    @Override
    public Result queryById(Long id) {
//        Shop shop = cacheClient.queryWithPassThrough(CACHE_SHOP_KEY,id, Shop.class, this::getById,
//                CACHE_SHOP_TTL,TimeUnit.MINUTES);
//        Shop shop = queryWithPassMutex(id);
        Shop shop = queryWithLogicalExpire(id);
        return Result.ok(shop);
    }
    //线程池
    private static final ExecutorService CACHE_REBUILD_EXECUTOR= Executors.newFixedThreadPool(10);
    //逻辑过期解决缓存击穿
    public Shop queryWithLogicalExpire(Long id){
        String redisKey=CACHE_SHOP_KEY + id;
        //1.先从redis查询数据
        String shopJsonStr = stringRedisTemplate.opsForValue().get(redisKey);
        //2.命中直接返回
        if (StrUtil.isBlank(shopJsonStr)){
            return null;
        }
        //3.命中，需要先把json反序列化为对象
        RedisData redisData = JSONUtil.toBean(shopJsonStr, RedisData.class);
        JSONObject data =(JSONObject) redisData.getData();
        Shop shop = JSONUtil.toBean(data, Shop.class);
        LocalDateTime expireTime = redisData.getExpireTime();
        //4.判断是否过期
        if (expireTime.isAfter(LocalDateTime.now())){
            //4.1未过期，直接返回
            return shop;
        }

        //4.2已经过期,缓存重建
        //5.1获取互斥锁
        String lockKey=LOCK_SHOP_KEY+id;
        boolean isFlag = tryLock(lockKey);
        //5.2判断是否获取互斥锁成功
        if (isFlag){
            //5.3成功，获取独立线程，实现缓存重建
            CACHE_REBUILD_EXECUTOR.submit(()->{
                try {
                    saveToCache(id,20L);
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }finally {
                    unLock(lockKey);
                }
            });

        }
        //5.4失败，返回信息
        return shop;
    }

    //解决缓存穿透代码
    public Shop queryWithPassThrough(Long id){
        String redisKey=CACHE_SHOP_KEY + id;
        //1.先从redis查询数据
        String shopJsonStr = stringRedisTemplate.opsForValue().get(redisKey);
        //2.命中直接返回
        if (StrUtil.isNotBlank(shopJsonStr)){
            Shop shop = JSONUtil.toBean(shopJsonStr, Shop.class);
            return shop;
        }
        //判断是否为空值
        if (shopJsonStr!=null){
            return null;
        }
        //3.未命中从数据库查询   数据库查询不到也要写入缓存，防止缓存穿透(布隆过滤，缓存空对象)
        Shop shop = getById(id);
        if (shop==null){
            stringRedisTemplate.opsForValue().set(redisKey,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
            return null;
        }
        //5.存在将数据写入redis value形式
        String shopStr = JSONUtil.toJsonStr(shop);
        stringRedisTemplate.opsForValue().set(redisKey,shopStr,CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        hashmap形式
//        Map<String, Object> shopMap = BeanUtil.beanToMap(shop, new HashMap<>(),
//                CopyOptions.create()
//                        .setIgnoreNullValue(true)
//                        .setFieldValueEditor((fieldName, fieldValue) -> fieldValue != null ? fieldValue.toString() : null));
//        stringRedisTemplate.opsForHash().putAll(redisKey,shopMap);
        return shop;
    }

    //获取分布式锁解决缓存击穿问题
    public Shop queryWithPassMutex(Long id){
        String redisKey=CACHE_SHOP_KEY + id;
        //1.先从redis查询数据
        String shopJsonStr = stringRedisTemplate.opsForValue().get(redisKey);
        //2.命中直接返回
        if (StrUtil.isNotBlank(shopJsonStr)){
           return JSONUtil.toBean(shopJsonStr, Shop.class);
        }
        //判断是否为空值
        if (shopJsonStr!=null){
            return null;
        }
        String key=LOCK_SHOP_KEY+id;
        Shop shop = null;
        try {
            boolean flag = tryLock(key);
            if (!flag){
                Thread.sleep(50);
               return queryWithPassMutex(id);
            }
            //3.未命中从数据库查询   数据库查询不到也要写入缓存，防止缓存穿透(布隆过滤，缓存空对象)
            shop = getById(id);
            if (shop==null){
                stringRedisTemplate.opsForValue().set(redisKey,"",CACHE_NULL_TTL,TimeUnit.MINUTES);
                return null;
            }
            //5.存在将数据写入redis value形式
            String shopStr = JSONUtil.toJsonStr(shop);
            stringRedisTemplate.opsForValue().set(redisKey,shopStr,CACHE_SHOP_TTL, TimeUnit.MINUTES);
//        hashmap形式
//        Map<String, Object> shopMap = BeanUtil.beanToMap(shop, new HashMap<>(),
//                CopyOptions.create()
//                        .setIgnoreNullValue(true)
//                        .setFieldValueEditor((fieldName, fieldValue) -> fieldValue != null ? fieldValue.toString() : null));
//        stringRedisTemplate.opsForHash().putAll(redisKey,shopMap);
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }finally {
            unLock(key);
        }
        return shop;
    }



    //获取互斥锁，解决缓存及击穿，当热点key突然失效，且重建缓存业务复杂的时候，大量请求会给数据库带来压力
    private boolean tryLock(String key){
        Boolean flag = stringRedisTemplate.opsForValue().setIfAbsent(key, "1", 10, TimeUnit.SECONDS);
        return BooleanUtil.isTrue(flag);
    }
    //删除锁
    private void unLock(String key){
        stringRedisTemplate.delete(key);
    }

    //将热点数据提前写入缓存
    public void saveToCache(Long id,Long expireTime){
        //1.查数据库
        Shop shop = getById(id);
        //2.封装逻辑过期时间
        RedisData redisData=new RedisData();
        redisData.setData(shop);
        redisData.setExpireTime(LocalDateTime.now().plusSeconds(expireTime));
        //3.写入redis
        stringRedisTemplate.opsForValue().set(CACHE_SHOP_KEY+id,JSONUtil.toJsonStr(redisData));
    }

    @Override
    @Transactional//确保一致性，要成功都成功。
    public Result updateShop(Shop shop) {
        Long id = shop.getId();
        if (id==null){
            return Result.ok("要修改的店铺不存在");
        }
        updateById(shop);
        //先更新数据库，在删除缓存
        stringRedisTemplate.delete(CACHE_SHOP_KEY+id);
        return Result.ok();
    }

    @Override
    public Result queryShopByType(Integer typeId, Integer current, Double x, Double y) {
        //1.判断是否需要根据坐标查询
        if (x==null || y==null){
            //不需要坐标查询，按照数据库查询
            Page<Shop> page = query().eq("type_id", typeId)
                    .page(new Page<>(current, SystemConstants.DEFAULT_PAGE_SIZE));
            return Result.ok(page.getRecords());
        }
        //2.计算分页参数
        //2.1从哪开始
        int from=(current-1)*SystemConstants.DEFAULT_PAGE_SIZE;
        //2.2到哪结束
        int end=current*SystemConstants.DEFAULT_PAGE_SIZE;
        //3.查询redis，按照距离排序，分页  结果：shopId  distance
        String key=SHOP_GEO_KEY+typeId;
        GeoResults<RedisGeoCommands.GeoLocation<String>> results = stringRedisTemplate.opsForGeo().search(
                key,
                GeoReference.fromCoordinate(x, y),
                new Distance(5000),
                RedisGeoCommands.GeoSearchCommandArgs.newGeoSearchArgs().includeCoordinates().limit(end)
        );

        //4.解析出id
        if (results==null){
            return Result.ok(Collections.emptyList());
        }
        List<GeoResult<RedisGeoCommands.GeoLocation<String>>> list = results.getContent();
        if (list.size()<=from){
            //没有下一页
            return Result.ok(Collections.emptyList());
        }
        //4.1 截取from-end的部分
        List<Long> ids=new ArrayList<>(list.size());
        Map<String,Distance> distanceMap=new HashMap<>(list.size());
        list.stream().skip(from).forEach(result->{
            //4.2获取店铺id
            String shopIdStr = result.getContent().getName();
            ids.add(Long.valueOf(shopIdStr));
            //4.3获取距离
            Distance distance = result.getDistance();
            distanceMap.put(shopIdStr,distance);
        });
        //5.根据id查询店铺信息
        String idStr = StrUtil.join(",", ids);
        List<Shop> shops = query().in("id", ids).last("ORDER BY FIELD(id," + idStr + ")").list();
        for (Shop shop : shops) {
            shop.setDistance(distanceMap.get(shop.getId().toString()).getValue());
        }

        //6.返回结果
        return Result.ok(shops);
    }
}
